I purchased some microfibbets for use as tails when tying mayfly imitations. The fibers I've purchased are 3-4 times longer than the mayfly tails I intend to tie. Therefore can I cut the fibers into 3rds so I can get 3 times the number of tails from a given package of microfibbets?

Are the microfibbets the same throughout their entire length or are they designed with a specified tail end? Are the fibers hollow, such that using a cut microfibbet for a mayfly tail would not perform as well as an uncut fiber? If they are indeed hollow fibers would exposing a cut end cause the fibers to absorb water?

Just wondering if a microfibbet changes in its stiffness and/or floatability, depending on whether you use the end or middle sections of the fiber?

Microfibbets are not hollow, they are made entirely of a solid plastic (nylon actually) that is the same material used in high quality synthetic paint brushes. They are tapered at the tip end, and this is why cutting them to get more flies out of a package is not a good idea. They have the same stiffness throughout, the difference being that the tip end is finer (smaller diameter); therefore, the tip is slightly more flexible.

I use Microfibbets exclusively on flies like comparaduns or spinner imitations. I simply tie them in just like splayed hackle fiber tails and then cut the butt ends of the fibers after they are tied in (again, just like with hackle fiber or hair tails).

Microfibbets are uniform in size, making it easy to tie the fly because you don't need to measure a hackle feather to get the right size. And they are stronger than hackle fibers, which makes it very easy to adjust the length of the tail without harming the fibers.